The present invention relates to pens, and relates more particularly to such a pen which can be conveniently operated to extend the refill out of the barrel for writing, or to receive the refill back to the inside of the barrel when not in use.
Regular pens are commonly equipped with a press button or rotary cap adapted for controlling the position of the refill. When the press button is pressed down or the rotary cap is twisted clockwise, the refill is forced out of the barrel for writing. After writing, the press button is released or the rotary cap is twisted counter-clockwise, thereby causing the refill to be received back inside the barrel. The mechanism which is coupled between the refill and the rotary cap/press button cap tends to be damaged after long uses of the rotary cap/press button cap, thereby causing the pen unable to work properly.